Characterization and analysis of repetitive DNA in Pseudis (Anura, Hylidae): sex chromosomes, comparative mapping and satellite DNA dynamics

Abstract

Repetitive DNA compose the major part of the eukaryotes genomes, being divided in two major classes: (a) in tandem repetitive DNA and (b) dispersed repetitive DNA. Among in tandem repetitive DNA there are satellite DNA, the major components of the heterochromatin, and the multigenic families as the array of histone genes. The intrinsic repetitive nature of these sequences always presented difficulties to better characterize them in studies of genome sequencing and assembling. However, new methods have arisen to better study these portions of the genome using sequences generated by next generation sequencing (NGS) approaches. Using NGS and bioinformatic tools it now possible to study deeply the repetitive DNA composition in a given genome, as well as to investigate the evolution of these sequences and also to generate new cytogenetic markers for chromosome homeology recognition in closely related species. In the present project it is proposed to characterize the library of satellite DNA in the anuran Pseudis tocantins from NGS reads using algorithms developed for the study of repetitive DNA sequences. In addition, we propose to isolate and mapping the sequences characterized for P. tocantins in other three species of Pseudis and one of Lysapsus in order to investigate the dynamic of repetitive DNA sequences, as well as to infer events of chromosome evolution in the genus Pseudis. We also intend to isolate, characterize and map sequences from multigenic families (e.g. histone genes) to infer chromosome homeologies and to test the applicability of this approach to survey taxonomic/filogenetic informative characters for the genus Pseudis. Lastly, we propose to test the hypothesis of existence of other satellites DNAs that could be present in the chromosome W of P. tocantins and to identify repetitive DNA sequences that could be exclusive of the Z chromosome of this species.